Sulfates chemical resistance

To calibrate the cobalt source, three systems are most often used ferrous sulfate, ferrous sulfate-cupric sulfate, and ceric sulfate. Dosimeters of these solutions are prepared by filling 5-ml. chemical-resistant glass ampoules with approximately 5 ml. of solution and flame-sealing the ampoules. The ampoules are then arranged in phantoms of Masonite or similar materials (Figure 13) to simulate the food items. These phantoms are placed in containers similar to those used for food products, and arranged in the conveyor carrier in which they are transported into the irradiation cell. Because of the upper dose limit of the ferrous sulfate and ferrous sulfate-cupric sulfate dosimeters (40,000 and 800,000 rads, respectively), these systems can be used only to establish the dose rate in the facility and not to monitor the total dose during food irradiation. The ceric dosimeter which... 

Aluminum borate whiskers are produced commercially by an external flux method. Chlorides, sulfates, or carbonates of alkali metals are added to alumina and boric oxide (or boric acid) and the mixture is heated to 800°C-1000°C to produce aluminum borate whisker (length 10-30 pm and diameter 0.5-1.0 pm). It has a melting point of 1440°C, a very low coefficient of thermal expansion, and an excellent chemical resistance toward acids. The aluminum borate whisker was reported to be effective in improving not only the thermal degradation but also the glass transition temperature of epoxy76... 

Barium sulfate has found many applications mainly because of its unique chemical resistance and inertness (for example, it is not affected by acid rain). The other reason for its frequent application is high absorptivity of light and, significantly. X-rays (for use in X-ray detectable materials). 

Aluminate compositions include calcium aluminate cements, which have high chemical resistance, especially to sulfate, and is also used in refractory applications where ordinary Portland cements would be unsuitable. These same cements are used in bioceramic applications. The bioceramic applications reflect both the high mechanical strength of the calcium aluminate cements and also the biocompatibility of Ca-bearing phases, which bond well with, for example, bone. 

Astra Bar. [ECXIIntT.] Barium sulfate rubber additive imparts high density, chemical inertness, sound deadening, chemical resistance. 

The chemical resistance of latex-modified mortar and concrete is dependent on the nature of polymers added, polymer-cement ratio and the nature of the chemicals. Most latex-modified mortars and concretes are attacked by inorganic or organic acids and sulfates since they contain hydrated cement that is non-resistant to these chemical agents, but resist alkalis and various salts except the sulfates. Their chemical resistance is generally rated as good to fats and oils, but poor to organic solvents. 

Tetrafluoroethylene/propylene copolymer molding resins, phenolic food-contact Acetaldehyde m-Cresol moldings, building industry Calcium sulfate hemihydrate moldings, chemical-resistant Tetrafluoroethylene/perfluoro (propyl vinyl ether) copolymer... 

One of the most useful properties of lead is its ability to absorb nuclear and X-ray radiation. Lead has good chemical resistance but is attacked by nitric and organic acids. Lead is extremely resistant to atmospheric corrosion as it rapidly becomes covered with an impervious film of oxides, carbonates, and sulfates. 

Calcium Sulfate 25 22 7 8 Resistant - no visual change Chemical resistance per ASTM Lustran Monsanto Specimen 50.8 mm... 

The methacrylic backbone structure makes the spherical Toyopearl particles rigid, which in turn allows linear pressure flow curves up to nearly 120 psi (<10 bar), as seen in Fig. 4.45. Toyopearl HW resins are highly resistant to chemical and microbial attack and are stable over a wide pH range (pH 2-12 for operation, and from pH 1 to 13 for routine cleaning and sanitization). Toyopearl HW resins are compatible with solvents such as methanol, ethanol, acetone, isopropanol, -propanol, and chloroform. Toyopearl HW media have been used with harsh denaturants such as guanidine chloride, sodium dodecyl sulfate, and urea with no loss of efficiency or resolution (40). Studies in which Toyopearl HW media were exposed to 50% trifluoroacetic acid at 40°C for 4 weeks revealed no change in the retention of various proteins. Similarly, the repeated exposure of Toyopearl HW-55S to 0.1 N NaOH did not change retention times or efficiencies for marker compounds (41). 

In addition to the four compounds discussed above, the final Portland cement may contain gypsum, alkali sulfates, magnesia, free lime and other components. These do not significantly affect the properties of the set cement, but they can influence rates of hydration, resistance to chemical attack and slurry properties. 

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